How to choose the Right Material based on your Application

The industries and manufacturing plants operate in a range of environments and use a wide variety of alloys so that the industrial processes can be more efficient, resistant to corrosion and heat and can be more sustainable and cost effective. Here is a list and description of different kinds of alloys used in the modern industrial environments.

Nickel and its alloys

The highly versatile and corrosion resistant metal Nickel combines with many metals. The metal’s symbol is Ni, and it has an atomic number of 28. The metal is silvery white in its appearance with a slightly golden tinge. The ductile and hard metal exhibits a significant amount of chemical activity.

Nickel oxidizes very slowly at room temperature, and that is why it has high corrosion resistance. It is used widely for coating metals like iron and alloys like brass apart from coating chemistry equipment. Around 60% of the metal produced (around the world) is used for nickel-steel alloys. It is also combined with other metals like Molybdenum and Chromium among others to form Superalloys like Hastelloy. A Superalloy (also called as high-performance alloy) has best-in-class mechanical strength, excellent resistance to corrosion, good stability at the surface and is resistant to creep-deformations caused by heat.

Nickel availability for industrial applications

Nickel is mostly produced in 200 and 201 forms and which consist of 99% nickel. The strength of other elements varies.

The 2 alloys of nickel viz. 200 and 201 offer good resistance in neutral and reducing media and also resists corrosion caused by oxidizing media and atmosphere by forming a passive-oxide surface layers,

Nickel applications

Electronics

Petrochemical and chemical processing

Food and fiber processing equipment (so that product purity can be ensured)

Hastelloy is a nickel-steel alloy that is classified as a Superalloy. The alloy is highly resistant to stress corrosion and cracking and offers ease of fabrication and welding. The alloy has a multitude of industrial applications and is used in marine and aerospace industries and in chemical processing, industrial gas turbine, pharmaceutical and oil/gas industry.

Well Known Hastelloy Grades are:

HASTELLOY C276

ALLOY C-276

UNS N10276

HASTELLOY C22

ALLOY C-22

UNS N06022

HASTELLOY B2

ALLOY B-2

UNS N10665

HASTELLOY C4

ALLOY C-4

UNS N06455

Ni

Cr

Fe

Mo

Co

W

C

Mn

Si

B

47%

22%

18%

9%

1.5%

0.6%

0.10%

1%

1%

0.008%

Hastelloy: Nominal weight percent and chemical composition

Hastelloy: Oxidation Resistance

The alloy has the best combination for resisting oxidation, has the best fabricability and a good strength at high temperature. It is used in petrochemical applications as it resists cracking caused by stress corrosion to a greater extent. The alloy is sufficiently ductile when exposed to a temperature of 650, 760 and 870 degree Celsius for around 16,000-hour duration.

Easy to Fabricate

The alloy offers better and superior welding and forming characteristics. As it is ductile, it can be cold worked easily. It can be welded by both automatic and manual methods like a gas-tungsten arc, shielded metal arc, and gas-metal arc.

Heat Treatment

Hastelloy’s wrought forms are industrially furnished in the solution and heat-treated conditions at around 1177 degree Celsius and then cooled rapidly in hydrogen.

Industrial Applications

The alloy is used in aerospace, chemical and furnace process equipment. It is used widely for manufacturing the combustion zone components of the gas turbine engines like combustor cans, transition ducts, flame holder and spray bars among other equipment. As it resists oxidization, it is used in industrial furnace applications as well. The industrial furnace tools made of the alloy were found to be in good condition even when they operated for around 8,700 hours at 1117 degree Celsius. In chemical processing, the alloy is used in the form of furnace baffles, muffles, catalyst support grids and in a flash- drier components among other equipment and parts.

Monel is also a nickel alloy and contains around 67 % of nickel and 28 to 34 % of copper along with small amounts of other elements like silicon, manganese, iron, and carbon. Monel alloys available today include Monel 400, 401, 404 K-500 and R-405. Monel is the preferred alloy when non-magnetic characteristics are desired.

Monel Grades available with us are:

Monel 400

ALLOY 400

UNS N04400

Monel K500

ALLOY K500

UNS N05500

Ni

C

Mn

Fe

S

Si

Cu

63%

0 duhv1nk.3%

2%

2.5%

0.024%

0.5%

28-34%

Monel: Nominal composition

Hardness and tensile strength

Monel has best-in-class mechanical properties even at sub-zero temperatures. The hardness and strength of the alloy can be increased by only fractionally and marginally impairing its impact-resistance and strength. The alloy does not become brittle even when cooled at liquid hydrogen temperature. It has best-in-class fracture characteristics and good ductility. The alloy sets the toughness example and has consistent strength over a range of different temperatures.

Corrosion Resistance

Monel can better resist attacks by the oxidizing media in comparison to the copper-based alloys and hence is used in different kinds of environments.

Key characteristics of Monel

Malleable

Resistant to alkaline substances and solutions

Offers high resistance to a range of high-power acids like sulfuric acid and hydrofluoric acid

Much stronger than stainless steel

Best-in-class corrosion resistance

Industrial Applications

Monel finds its applications in Aerospace, Oil production/refining and marine industry as it has excellent corrosion resistant properties. It is also used in the manufacture of musical instruments and directional drilling.

Hence, Monel is used in marine components, instruments, oil well tools, pump shafts, valve trim, valves, shafts, pumps, heat exchangers and fittings. It is also used in equipment relating to the processing of hydrocarbons and chemicals.

Incoloy is a nickel Superalloy. The alloy can resist corrosion caused by most powerful acids including sulfuric acid. The alloy has high strength even at high temperature and offers good corrosion resistant properties. Incoloy is available in grades like 020, DS, MA 956, 800 and 825 among others. The nickel and chromium based alloy also has other elements like copper, molybdenum. The other elements and metals added in small amounts, including manganese, carbon, silicon, sulfur, tantalum, and niobium.

Best-in-class resistance to corrosion in the marine and aqueous environment

Industrial applications of Incoloy

Incoloy is used in industrial equipment like heat exchangers, process piping, and tubing of nuclear steam generators. It also finds its use in power plants, petrochemical and chemical processing, equipment for heat-treating and re-processing of nuclear fuel, equipment for pollution control, pickling equipment, acid production and oil/gas well piping among others.

Inconel is a nickel, chromium based austenite alloy. The name is a trademark of USA based refractory alloy supplier Special Metal Corporation. Inconel alloys have corrosion resistant and oxidation resisting properties. The alloy forms a passivating, stable and a thick oxide layer that is capable of protecting its surface from corrosive and acid attacks. The alloy has high strength retaining the ability and wide temperatures range. That is why it used for high-temperature industrial applications.

Inconel is available in a range of alloy forms, including Inconel 600, 617, 625, 690, 718 and 750. The alloy contains nickel (44 to 72%), chromium (14 to 30%
), iron (3 to 10%), molybdenum (2 to 10%), manganese (0.35 to 1%), copper (0.5 to 8%), aluminum (0.4 to 1.15%), titanium (0.3 to 2.75%), silicon (0.35 to 0.5 %) and carbon (0.08 to 0.15%). Some forms of alloy also contain sulfur, phosphorus, niobium and boron.

Stainless steel is also known by other names like “Inox” or “Inox steel”.To be classified as stainless steel, the alloy must have at-least 10.5% chromium. Stainless steel is more capable of resisting stain, rust and corrosion in comparison to ordinary steel. Chromium forms a passive chromium oxide layer and prevents surface corrosion by blocking the diffusion of oxygen.

Applications

Stainless steel is used in power generation, chemical, procession, oil/gas and food production industry. It is also used widely in construction, architecture, and the automotive industry and has wide usage in manufacturing of medical applications like orthopedic beds, examination machines, and cabinets.

Stainless steel can be classified in 7 different categories.

Ferritic stainless steel

Ferritic stainless steel has more suitable engineering properties in comparison to the austenitic grade steels but has lower resistance to corrosion. This is so because it has lower nickel and chromium content. Their body-centered cubic design had 10 to 27% of chromium with little amounts of nickel. They also contain titanium or aluminum and molybdenum.

The major alloy element is chromium (10 to 27%)

Magnetic in nature

Good resistance to corrosion

Can be hardened further by heat treatment

Common grades include 409, 410-S AND 430

Austenitic stainless steel

This steel grade is also referred as 200 and 300 series grade. The particles have a face-centered cubic-crystal structure.

70% of total stainless steel produced belongs to this grade

Can be harden by cold working

Non magnetic in nature

Better yield strength and hardness

Contains a minimum Chromium strength of 16% and maximum carbon strength of 0.015%

Common grades of this steel include 304, 309, 316, 321, 320 and 347. Steels classified as super austenitic steels like 245 SMO and AL-6XN have higher crevice corrosion and chloride-pitting resistant properties.

Martensitic stainless steel

This steel grade is highly strong but has lower corrosion resistant property. It has a body centered cubic crystal design.

Tough and strong

Machinable

Can be hardened further by providing heat treatment

Contains 12 to 14% of chromium, 0.2 to 1% of molybdenum, less than 2% of nickel and less than 1% of carbon

Duplex steel or duplex stainless steels have a 2-phase microstructure and consist of grains of ferrite and austenite stainless steel, with the two ingredients mostly added in a 50:50 ratio. Duplex stainless steels are two times more powerful than the regular steel and also offer better resistance to all kinds of corrosion including crevice, pitting, tress and localized corrosion. These steels consist of high chromium content of 19 to 32% and around 5% of molybdenum content. Duplex steel has lower amounts of nickel in comparison to austenitic stainless steel. Duplex stainless steel is more cost effective and has lower content of alloys somewhat. Based on their corrosion resistance and alloy content, the duplex stainless steels are characterized by many different kinds of classes.

Lean duplex- It has duplex stainless steel grades including S-32202, S-32003 and S-32304 and UNS S32101.

Standard duplex- Has 22% of chromium content. UNS 31803 & UNS S32205 is the most widely used variant.

Super duplex– This variant has a PREN (Pitting Resistant Equivalent Number) greater than 40. PREN measures corrosion resistance. This variant has 25% of chromium content or even more. Variants include S-32750, S-32760, and S-32550.

Hyper duplex- the duplex steel offers greater corrosion resistance and is available in UNS S-32707 and S-33207 variants.